Developing device

A developing device comprising:

• a developing roll;
• a supply screw which conveys developer in axial direction to supply said developer for said developing roll;
• a collection screw which collects developer left on said developing roll and conveys said developer in axial direction;
• and
• an agitating screw which agitates developer and conveys said developer in axial direction;
• wherein
• said collection screw is arranged below said supply screw and said agitating screw is arranged above said supply screw, conveying force by upper screw is made to be larger than conveying force by lower screw within at least one of first carry-up area and second carry-up area, said first carry-up area where developer is carried up to said supply screw from said collection screw, said second carry-up area where developer is carried up to said agitating screw from said supply screw, and said first carry-up area is arranged at far more downstream side for said collection screw's conveying direction than at said second carry up area.

A developing device comprising:

• a first screw and a second screw to convey developer in axial direction;
• and
• delivery area where developer is delivered to said second screw from said first screw or vice versa, wherein
• larger diameter screw blade part is applied to said delivery area for at least one of said first screw and said second screw.

A developing device comprising:

• a developer storage tank;
• and
• a first screw and a second screw both arranged inside of said developer storage tank to convey developer;
• wherein
• delivery area where developer is delivered from said second screw to said first screw or vice versa is arranged at downstream for conveying direction of giving side's screw, and inner surface of said developer storage tank is curved surface at said delivery area.

A developing device comprising:

• a developer storage tank;
• and
• a first screw and a second screw both arranged inside of said developer storage tank to convey developer;
• wherein
• delivery area where developer is delivered from said first screw to said second screw or vice versa is arranged at downstream of conveying direction for giving side's screw, and inner surface of said developer storage tank is tapered surface at said delivery area.

A developing device comprising:

• a developer storage tank;
• and
• a first screw and a second screw both arranged inside of said developer storage tank to convey developer;
• wherein
• delivery area where developer is delivered from said first screw to said second screw or vice versa is applied at downstream of conveying direction for giving side's screw, and conveying force by said giving side's screw is made to be smaller at said delivery area than other area.